Visual processing and saccadic eye movements are integral aspects of reading. The proposed research investigates the relationship between saccadic eye movements and visual processing, and thus may provide information useful in the understanding of dyslexia. Eye movements in the cat and monkey are accompanied by gross electrical potentials (PGO waves) in lateral geniculate nucleus (LGN) and other sites in the central nervous system. The working assumption of the present research is that these PGO waves are the electrical sign of an active process related to vision during eye movements. Two such active processes have been described previously: "saccadic suppression" of visual detection and "corollary discharge." Evidence is herein presented which suggests that the LGN PGO waves are related to a third, thus far undescribed, activity process which is tentatively named "fixation augmentation" of visual detection. The purpose of the proposed research is twofold: 1) to analyze changes in visual system function correlated with LGN PGO waves in primates, and 2) to conduct parallel experiments in humans, correlating changes in visual system function with visual fixation. Previous research has shown that: 1) LGN PGO waves are a result of eye movement-correlated phasic activation of midbrain reticular formation (MRF) and, 2) electrical stimulation of MRF results in changes of receptive field size for neurons of LGN. We will investigate the possibility that receptive field characteristics are altered as a correlate of LGN PGO waves. Behavioral experiments have also shown that recognition of visual targets during brief tachistoscopic presentation is improved by electrical stimulation of MRF in monkeys. We will seek behavioral correlates of LGN PGO waves in primates, investigating changes, for example, in form recognition, visual acuity, peripheral vision and response time as a function of LGN PGO waves. Since LGN PGO waves are precisely correlated with the termination of saccadic eye movements, human subjects will be studied to investigate similar changes in visual function correlated with saccade termination. BIBLIOGRAPHIC REFERENCE: Mendell, L. M, Munson, J. B. and Scott, J. G. Alterations of synapses on axotomized motoneurons. J. Physiol. 1976, 255, 67-79.